1. Field of the Invention
The present invention relates to a process for removing chlorine ions from wet flue-gas processing system.
2. Description of the prior art
For a wet flue-gas processing system, various procedures have hitherto been employed to completely avoid the formation of waste water in order to prevent pollution. These procedures, however, suffer from the disadvantage in that small amounts of chlorine contained in industrial water, heavy fuel oil, the reagents employed, and the like are concentrated and accumulated in the circulating absorbing solution during the processing. When the chlorine concentration in the circulating absorbing solution reaches 4,000 to 6,000 ppm, stress corrosion cracking, pitching corrosion, etc., of stainless steel, of which an absorbing tower and the like are principally. Therefore, it has long been desired to effectively remove chlorine ions.
In the past, in order to remove the disadvantages due to the accumulation of chlorine ions, a part or the whole of the circulating absorbing solution has been withdrawn from the processing system when the chlorine ion concentration reaches a predetermined level.
This procedure, however, has the disadvantages in that it is difficult to the circulating absorbing solution withdrawn and when abandoned, secondary pollution results. In addition, the economic disadvantages take place in that fresh absorbing solution must be added in an amount corresponding to that of the absorbing solution withdrawn, and in that large amounts of dissolved salts are contained in the absorbing solution withdrawn and therefore lost.